According to the recent trend of high functionality of electronic devices and expansion of their use to mobile applications, there is an increasing demand for developing a semiconductor device having high density and high integration. As a result, an IC package having high capacity and high density is developed. In a method for manufacturing the semiconductor device, an adhesive sheet is, first, attached to a semiconductor wafer made of silicon, gallium, arsenic or the like, and then the semiconductor wafer is diced (or segmented) into individual semiconductor elements. Next, the semiconductor elements thus segmented are separated from each other by expanding the adhesive sheet, picked up, and then die-bonded to a metal lead frame, a tape substrate or an organic hard substrate, to thereby obtain the semiconductor device.
Further, there is remarkable technological innovation for a semiconductor device having lightness and compactness. Thus, various package structures for the semiconductor device have been proposed and the semiconductor device having such a structure has been produced. In recent years, in place of such a conventional method for mounting a semiconductor element on a lead frame, an area mounting method, in which a semiconductor element having a circuit surface (functional surface) and a circuit substrate are bonded together through a plurality of protruding electrodes directly formed on the functional surface of the semiconductor element, is becoming a dominant method.
As the typical area mounting method, a flip-chip mounting method is used. In the flip-chip mounting method, generally, a gap between the semiconductor element and the circuit substrate is sealed with a resin composition to reinforce a joint portion through which the semiconductor element and the circuit substrate are bonded together and to improve reliability of a semiconductor device obtained by bonding the semiconductor element and the circuit substrate together.
Further, a method for manufacturing a stacked package by sterically stacking (laminating) a plurality of semiconductor elements together is also becoming a dominant mounting method. In the method for manufacturing a stacked package, since the plurality of semiconductor elements are arranged in a sterical manner rather than in a planar manner, a compact package (semiconductor device) can be manufactured. Further, since such a package contains the plurality of semiconductor elements, it can process a large amount of information, thereby improving overall performance thereof.
As one of techniques for manufacturing a stacked package by sterically stacking a plurality of semiconductor elements, there is a technique called Multi-Chip Package (MCP) in which a plurality of semiconductor elements are sterically stacked and electrically connected together via bonding wires to manufacture the stacked package.
In contrast, as the other technique, there is a technique in which a plurality of semiconductor elements are sterically stacked and electrically connected together via electrodes passing through each semiconductor element in a thickness direction thereof (Through Silicon Via (TSV)). In the TSV technique, through-holes are formed in each semiconductor element in the thickness direction thereof and filled with metal, and then the semiconductor elements are electrically connected together via the metal. According to such a method, since no bonding wires are needed to electrically connect the semiconductor elements, there is a merit that a distance between the semiconductor elements can be shortened. For this reason, the TSV technique will become a dominant technique for sterically stacking a plurality of semiconductor elements.
In this regard, in such a TSV technique, generally, a gap between the semiconductor elements is also sealed with a resin composition to reinforce a joint portion through which the semiconductor elements are bonded together and to improve reliability of a semiconductor device obtained by bonding the semiconductor elements together.
As such a sealing method with the resin composition, a capillary underfill method is generally used. In this method, a sealing resin composition in a liquid state is applied on a circuit substrate along one side or a plurality of sides of a semiconductor element provided on the circuit substrate, and then flowed into a gap between the semiconductor element and the circuit substrate by utilizing capillary phenomenon, to thereby seal the gap with the sealing resin composition (see patent document 1: JP-A-2007-217708).
However, in the capillary underfill method, a step of bonding the semiconductor element and the circuit substrate together using a flux and a step of cleaning (removing) the flux are required. Therefore, the time required for performing the above steps becomes long and environment management such as management of a waste solution after cleaning the flux must be severely carried out. Furthermore, since the sealing of the gap with the sealing resin composition is performed by utilizing the capillary phenomenon, the time required for sealing the gap becomes long. For these reasons, there is a problem in that the use of the capillary underfill method lowers productivity of the semiconductor device.
Further, in recent years, according to a demand for manufacturing a thin semiconductor package, a semiconductor element which has been, in advance, ground is often used in the semiconductor package. Such a ground semiconductor element can be obtained by attaching a backgrinding tape to an element functional surface of a processed semiconductor wafer, grinding a surface opposite to the element functional surface of the semiconductor wafer, removing the backgrinding tape from the semiconductor wafer, attaching a dicing tape to the element functional surface of the semiconductor wafer, and then dicing the semiconductor wafer. Since the ground semiconductor element has to be obtained through the above complicated steps, a more simple method for obtaining it is required. Further, there is a problem in that a thin ground semiconductor wafer is easily damaged when being transferred or handled.